Represents the schema of an SQL table in an abstract way. This class provides methods for manipulating the schema representation.
Inside migration files, the t object in {create_table}[rdoc-ref:SchemaStatements#create_table] is actually of this type:
class SomeMigration < ActiveRecord::Migration[5.0] def up create_table :foo do |t| puts t.class # => "ActiveRecord::ConnectionAdapters::TableDefinition" end end def down ... end end